Add @requires_webgpu, make WebGPU tests fail if unavailable (#21870)

This makes these tests safer so they won't just silently pass if you
happen to run against a browser/system where WebGPU isn't available
(currently including Chrome on Linux and Firefox/Safari).

Author: kainino0x

.circleci/config.yml

@@ -368,6 +368,7 @@ commands:
             # TODO: Do GL testing when https://bugzil.la/1375585 (lack of WebGL
             #       support in headless mode) resolves
             EMTEST_LACKS_GRAPHICS_HARDWARE: "1"
+            EMTEST_LACKS_WEBGPU: "1"
             EMTEST_LACKS_SOUND_HARDWARE: "1"
             # OffscreenCanvas support is not yet done in Firefox.
             EMTEST_LACKS_OFFSCREEN_CANVAS: "1"
@@ -797,6 +798,8 @@ jobs:
           test_targets: "other skip:other.test_native_link_error_message"
   test-browser-chrome:
     executor: bionic
+    environment:
+      EMTEST_LACKS_WEBGPU: "1"
     steps:
       - run-tests-chrome:
           title: "browser"
@@ -806,19 +809,24 @@ jobs:
             "
   test-browser-chrome-wasm64:
     executor: bionic
+    environment:
+      EMTEST_LACKS_WEBGPU: "1"
     steps:
       - run-tests-chrome:
           title: "browser64"
           test_targets: "browser64"
   test-browser-chrome-2gb:
     executor: bionic
+    environment:
+      EMTEST_LACKS_WEBGPU: "1"
     steps:
       - run-tests-chrome:
           title: "browser_2gb"
           test_targets: "browser_2gb"
   test-browser-chrome-wasm64-4gb:
     executor: bionic
     environment:
+      EMTEST_LACKS_WEBGPU: "1"
       EMTEST_SKIP_NODE_CANARY: "1"
     steps:
       - run-tests-chrome:

src/library_webgpu.js

@@ -15,10 +15,9 @@
  * on WebGL 1.0/2.0.
  *
  * To test this, run the following tests:
- * - test/runner.py other.test_webgpu_compiletest
+ * - test/runner.py 'other.test_webgpu*'
  * - EMTEST_BROWSER="/path/to/chrome --user-data-dir=chromeuserdata --enable-unsafe-webgpu" \
- *   test/runner.py browser.test_webgpu_basic_rendering
- *   (requires WebGPU to be available - otherwise the test will skip itself and pass)
+ *   test/runner.py 'browser.test_webgpu*'
  */
 
 {{{

test/test_browser.py

@@ -186,6 +186,7 @@ def decorated(self, *args, **kwargs):
 
 
 requires_graphics_hardware = skipExecIf(os.getenv('EMTEST_LACKS_GRAPHICS_HARDWARE'), 'This test requires graphics hardware')
+requires_webgpu = unittest.skipIf(os.getenv('EMTEST_LACKS_WEBGPU'), "This test requires WebGPU to be available")
 requires_sound_hardware = skipExecIf(os.getenv('EMTEST_LACKS_SOUND_HARDWARE'), 'This test requires sound hardware')
 requires_offscreen_canvas = skipExecIf(os.getenv('EMTEST_LACKS_OFFSCREEN_CANVAS'), 'This test requires a browser with OffscreenCanvas')
 
@@ -4518,16 +4519,16 @@ def test_webgl_simple_extensions(self, simple_enable_extensions, webgl_version):
     'closure_advanced': (['-sASSERTIONS', '--closure=1', '-O3'],),
     'main_module': (['-sMAIN_MODULE=1'],),
   })
-  @requires_graphics_hardware
+  @requires_webgpu
   def test_webgpu_basic_rendering(self, args):
     self.btest_exit('webgpu_basic_rendering.cpp', args=['-sUSE_WEBGPU'] + args)
 
-  @requires_graphics_hardware
+  @requires_webgpu
   def test_webgpu_required_limits(self):
     self.btest_exit('webgpu_required_limits.c', args=['-sUSE_WEBGPU', '-sASYNCIFY'])
 
   # TODO(#19645): Extend this test to proxied WebGPU when it's re-enabled.
-  @requires_graphics_hardware
+  @requires_webgpu
   def test_webgpu_basic_rendering_pthreads(self):
     self.btest_exit('webgpu_basic_rendering.cpp', args=['-sUSE_WEBGPU', '-pthread', '-sOFFSCREENCANVAS_SUPPORT'])
 

test/webgpu_basic_rendering.cpp

@@ -25,19 +25,6 @@ void GetDevice(void (*callback)(wgpu::Device)) {
         if (message) {
             printf("RequestAdapter: %s\n", message);
         }
-        if (status == WGPURequestAdapterStatus_Unavailable) {
-            printf("WebGPU unavailable; exiting cleanly\n");
-            // exit(0) (rather than emscripten_force_exit(0)) ensures there is
-            // no dangling keepalive.
-#if _REENTRANT
-            // FIXME: In multi-threaded builds this callback runs on the main
-            // which seems to be causing the runtime to stay alive here and
-            // results in the 99 being returned.
-            emscripten_force_exit(0);
-#else
-            exit(0);
-#endif
-        }
         assert(status == WGPURequestAdapterStatus_Success);
 
         wgpu::Adapter adapter = wgpu::Adapter::Acquire(cAdapter);

test/webgpu_required_limits.c

@@ -64,11 +64,6 @@ void on_adapter_request_ended(WGPURequestAdapterStatus status,
                               WGPUAdapter adapter,
                               char const* message,
                               void* userdata) {
-  if (status == WGPURequestAdapterStatus_Unavailable) {
-    printf("WebGPU unavailable; exiting cleanly\n");
-    exit(0);
-  }
-
   assert(status == WGPURequestAdapterStatus_Success);
 
   wgpuAdapterGetLimits(adapter, &adapter_supported_limits);